Jet propulsion apparatus



April l0, 1951 H. J. DE N4. MccoLLuM 2,548,804

JET PROPULSION APPARATUS Filed March 25, 1945 2 Sheets-Sheet l H. J. DE N. MCcoLLUM JET PROPULSION APPARATUS April 1o, 1951k A '2 Sheets-Sheet 2 Filed March 25, 1945 Patented Apr. 10, 1951 i UNiTEn JET PROPULSION APPARATUS ApplicationMarch 23, 1945, Serial N0. 584,362

8 Claims. l The present invention relates to jet propulsion apparatus and more particularlyto jet propelled aircraft.

One of the primary objects of the present i'nvention is to provide a new and improved jet y propulsion type aircraft wherein the reaction vof a jet is utilized to rotate an airplane propeller thereby to provide a more elicient slow speed airplane.

Another object of the present invention is to provide jet propelled aircraftrequiring but little apparatus and which may be used in connection with a variable pitch propeller.

A further object of the present invention is to provide a new and improved jet propulsion arparatus wherein the jet reaction drives a propeller and wherein the propeller in turn is utilized to drive a fuel pump.

lStill another object of the present invention is to provide a new and improved jet propelled propeller driven aircraft having new and improved means for supplying a combustible mixture to jet producing means mounted at the tips of the propeller blades and which, more specifically, includes means for supplying combustion air by aspirationv and wherein the air is aspirated by vaporiz'ed fuel at high pressure, thereby to mifnmize the amount of apparatus necessary and to increase the efciency of the apparatus.

Other objects and advantages of the present invention will becomemore apparent from the ensuing description, in the course of which reference is had to the accompanying drawings, in which Fig. 1 is a somewhat diagrammatic and mainly cross-sectional view through jet propulsion apparatus constructed in accordance with the present invention;

Fig. 2 is a fragmentary reduced scale perspective view, partly in section, of the variable pitch propeller of Fig. 1 and the jet producing means mounted at the tip of the propeller;

y Fig. 3 is a fragmentary enlarged axial view through the jet producing means mounted at the tip of a propeller blade;

Fig. 4 is a fragmentary cross-sectional view of the jet producing means taken along the line lle-4 of Fig. 3;

Fig. 5 is a vertical axial cross-,sectional view through fuel vaporizing means illustrated also in Fig. 1`; and v Fig. 6` is an enlarged fragmentary detail of the' A:fuel and air injecting means for the fuel vapor, izer.

.The present invention is in the nature of an improvement over the inventions disclosed and claimed in the copendng application, Serial No.

l vided by housings I Il and I4 and a connecting (Cl. V70-135.4)

587,927, led April 12, 1945, now abandoned, and Patent No. 2,502,332, issued March 28, 1950. In these applications there is disclosed jet propulsion apparatus having no power loss resulting from the furnishing of compressed air, as by a compressor, and operating at a lower temperature. The apparatus includes a fuel'vaporizer for supplying vaporized fuel at high temperature and pressure to a jet entraining and aspirating aii necessary for combustion. A portion of theheat of the products of combustion is used to vaporize the fuel. Accordingly, Vthe vapparatus operates at lower temperatures and requires no compressor.

The apparatus of the present invention includes a fuel vaporizer of the character rdescribed and it is utilized to supply a combustible mixture to jet producing means mounted at the tips of propellers, thereby to provide a simplied and more efficient slow speed propeller driven airplane.

Referring now to the drawings and mainly to Figs. 1 and 2, the jet propulsion apparatus is housed within a housing or nacelle l0 which is secured in conventional fashion to or made part of any airplane (not shown). A variable pitch propeller having hollow blades l2 is mounted in front of the nacelle and a housing i4 having a rounded closed front end is secured in front of the propeller. A streamlined construction is prohousing I6 surrounding the inner portions of the propeller blades. ,y

lThe propellers are rotated by jet producing means i8 mounted at the tips ofthe blades constructed and arranged to produce jets that are tangentially disposed` relative to the bladeY tips. The jet producing means, which will .be described in greater detail shortly, are, in substance, combustion chambers in which a combustible mixture is burned to provide high temperature and high pressure combustion products which escape to atmosphere through nozzles, whereby the propeller is rotated by the reaction of the jet.

`The combustible mixture of `air and fuel is produced by injecting vaporized fuel at high temperature and pressure into an injection tube and utilizing the fuel jet to entrain 'and aspirate the airv necessary for combustiorn The fuel is vaporized by a-vaporizer indicated as "a whole by reference character 2D having a fuel outlet connection 22 leading to a nozzle 2l! disposed axially of a. Venturi tube like mixing tube :26 fixedly securedto the propeller blade supporting means. The nozzle is located near the throat 28 of the tube, which has an enlarged trailing end 30 through which air is led to the tube.

Air is supplied to the mixing tube from atmosphere by a conduit 32 having a reverse bend in it and projecting beyond the front of the housing |0, which is provided with an aperture 34 for the conduit. In normal operation during flight, the air will thus ce at a relatively high pressure.

The combustible mixture is supplied to the jet producing means I8 at the tips of the blades by conduits 36 extending through and fixedly secured to move with the blades. The inner ends of the blades are located adjacent the outer ends of the branch conduits 38 at the front end of the mixing tube 28, the construction thus being such that propeller blades may be moved for pitch adjustment without in any way affecting the supply of combustible mixture to the jet producing means.

The fuel vaporizer 20, which is preferably located above the mixing tube is supplied with vap'orized high pressure and temperature fuel 'during normal operation through a branch conduit 48 terminating in a nozzle 42 axially disposed near the throat 44 of a Venturi-like mixing tube 46.,v In starting, a highly volatile fuel, such'as propane, is supplied to the mixing tube through a second nozzle 48. It injects air at a low pressure so that there is provided a combustible mixture which Will vaporize the fuel. In order to conserve heat the fuel connections 22 'and'll are covered by a heat insulating jacket 50.

` Air Vis supplied to the fuel vaporizer through a vconduit 52 leading'from the mixing tube 46 to the air inlet conduit 32.

y The combustible mixture is supplied to an lignition chamber 54 and thence to a combustion chamber 56 from which it is exhausted, as to atmosphere, through an exhaust pipe 58. The mixture in chamber 54 is ignited, at least initially, by an electrical igniter 60 secured to the chamber casing and supplied with current through conductor' I.

The fuel is vaporized by the hot products of combustion in chamber 56. It isl preferred that the fuel be vaporized in a coil 82 located near the chamber Wall, although other arrangements can be used. The fuel, which may be gasoline, is supplied to the coil` from suitable source through a high pressure fuel ine 64 leading to a pressure control valve 66.

'Ihe pressure control valve is preferably of a type fully described in the previously referred l to '.copending applications. In the instant case,

howevenit is adapted to be connected selectively to tWo different sources of fuel under pressure rather than to one. It is connected to a source ofgasoline (not shown but which may be a tank -in the aircraft) through a conduit 68, a fuel pump '|0, conduit 'I2 and an inlet fitting 'I4 attached to the lower end of the valve 66. pump 'ID is, in accordance with one of the features of the present invention, driven by the propeller through gearing indicated generally by reference character 16 and which will be described in complete detail hereinafter. In order to provide regulated quantities of fuel to the pump, the pressure control valve 66 is adapted to by-pass any undesiredexcess of liquid fuel back to the tank as through a relief passage defining conduit 'VLl Any leakage past the valve member (not shown) is returnedV to the tank through a second return conduit 'I8'. Adjustment of the pressure at which the control valve operates is effected through a suitable control actuatable through a rod 80.

The

In order that fuel may be supplied to the apparatus when the propeller is not rotating, there is provided a sec-ond source including a fuel pump 82 which is driven as by an electric motor 84 supplied with energy, when desired, through a conductor 86. The inlet side of the pump is connected to the fuel supply line 68 by a branch conduit 88 and to the valve fitting 'I4 through a conduit 90. Suitable means such as a springpressed ball valve 92 are provided to prevent a back flow of liquid through the motor driven 4pump 82 when the main fuel pump I0 is driven by the propeller.

AS heretofore indicated, the main fuel pump 'I0 is driven by the propeller which is rotated by the jet. propulsion apparatus. The fuel pump is driven through the previously referred to gearing 'I6 and a tubular sleeve-like extension 94 of the main propeller blade supporting structure 96. The tubular extension 94 thus rotates with the propeller and with the mixing tube 26 which eX- tends through and is secured to it. The rear end of the mixing tube 26 is preferably supported vwithin the tubular extension by a spider 98, While the forward end of the tube is supported in the propeller blade supporting structure.

The fuel pump '|10 is secured to the main supporting structure |00 which is suitably secured to the aircraft. The pump shaft |02 is connected to the tubular extension 94 through gears |04, |06 and |88, the first of Which is on the pump shaft and the last of which is on the sleeve 04. Thus, as the sleeve is rotated by the propeller, the pump is also rotated.

The tubular extension 94 and the propeller supporting structure 96, Which are preferably formed integral, are supported in the main supporting structure |00. `The supporting means includes a front bearing I |0, a rear thrust bearing II2, and an intermediate roller bearing I I4. Rotary lubricant seals I I6 and I8 are located at the front'and rear ends of the supporting structure and a third seal |20 is located intermediate the ends and closely adjacent the thrust bearing |I2.

The rear end of the tubular extension extends beyond the supporting structure and has mounted on it a pair of insulated slip rings |22 and |24, the

former of which is .connected by conductor |26to an electric motor |28'c0nstituting part Yof the.

mechanism controlling the pitch of the propeller. The motorv is operatively connected to bevel gears |30 and |32 flxedly connected to the inner ends of the propeller blades I2 by gearing indicated generally by reference character |34 and including a bevel gear |36 meshing with the bevel gears |30Y and |32. The pitch control mechanism may be of various types, that illustrated being a Curtiss electric propeller of a type Well known to those skilled in the art so that it need not be described in detail. The second slip ring |24 is connected by conductor |38 and branch conductors |40 and |42 to ignition means forming part of the jet producing means I8 at the propeller tips.

The jet producing means of the present inven- `tion is best illustrated in Figs. 2, 3 and 4 to which reference is now had. Each jet producing means includes a generally cylindrical ignition chamber |44 Vto which the combustible mixture supplying conduits 36 are connected and opening into'fa generally conical combustion chamber |46 having 'a nozzle defining escape opening |48 of small diameter at its trailing end. A'streamlined con'- figuration isgiven to the jet producing means by the shape of the combustion chamber and a gen- S erally rounded end cap E50 suitably secured as by Welding Vto the Ycombustion chamber and to the tip yof the hollow propeller blade I2. The Conilbus'tion chamber |46 is also secured to the propeller tip. Y

The combustible mixture supplied to the jet propulsion means is ignited by anelectrical igniter |52 secured to the ignition Ychamber 144.

It is believed that the operation of the apparatus of the present invention will be` fairly apparent from the .foregoing detailed description thereof but a brief review of the operation as a whole will be made. Inorder to start the apparatus, the fuel vaporizer is first brought to a high temperatur using the auxiliary source of fuel, which may be propane or butane supplied through ythe nozzle' 48. This is readily accomplished by suitable fuel control means such as a valve which may be opened to supply the fuel" to the vaporizer 20. At the same time the igniter-S is supplied With electric' current. The fuel injects air at relatively loW pressure, the air flowing through the conduits 32 and 52. The mixture is burned in the ignition and combustion chambers 52% and 56 of the vaporiz'er until the vaporizer is hot.` y

After the Vaporizer has been brought up to a high temperature, the electric motor driven fuel pump t2' is placed into operation. It pum'psffuel to the vaporizerl through the conduit 65, thevheat exchanger coil B2 within the vaporizer. The gasoline ris vaporized and the pressure gradually built up until the mixture supplied to the jet producing means I8 through the mixing tube 26 and the conduits 36 in the propeller blades starts to burn and the propeller starts turning. Some of this fuel is also supplied to the vaporizer through the nozzle d2.

The auxiliary fuel is shut off as soon as the vaporizer is hot enough to vaporize gasoline in sufficient quantity to keep the system in operation. Once the propeller starts turning, the auxiliary fuel pump can also be cut off because the main fuel pump '10, which is driven by the propeller, is effective to supply sumcient fuel to the vaporizer through the pressure control valve 66. Excess liquid fuel is returned to the storage tank through the by-pass conduit 16.

The apparatus of the present invention has many advantages. It is light in construction because it does not require any multiple stage air compressor and it operates at low temperatures. It can be constructed as a compact and simple unit which can be manufactured readily and economically and which constitutes a simple replaceable unit.

Having thus described the invention, what is claimed to be new and desired to be secured by Letters Patent is as follows:

l. Jet propelled aircraft, including in combination, a rotatable propeller having blades and combustion chamber jet producing means at the propeller blade tips, means including a mixing tube having an air intake and means supplying said mixing tube with vaporized fuel at a high pressure and a high temperature whereby air is mixed with the fuel by aspiration for supplying a combustible mixture, and means for conducting the combustible mixture to the combustion chamber jet producing means at said blade tips.

2. Jet propelled aircraft, including in combination, a rotatable propeller having blades and combustion chamber jet producing means at the propeller blade tips, means including a mixing tube rotated with the propeller having an air intake and stationary fuel injecting means exat the leading edge of the aircraft, conduit Int-3ans` connecting the discharge'end of said tube 'to the jet producing means, means for supplying" and injecting high pressure and high temperature vaporized fuel to said tube thereby to entrain and aspirateair with the fuel to produce a combustible mixture, said last mentioned means in,- cluding a fuel vaporizer, a second mixing tube having anfair intake and discharge end, means connecting the discharge end to said 'vaporizer,

vconduit means connecting the air intake of the last mentioned tube to 'first mentioned conduit means, and means for supplying fuel 'and lin*- jeeting the fuel into said last mentioned tube near said air intake to produce a combustible mixture for said vaporizer. Y

1l-Jet propelled aircraft, including in combination, a propeller having blades and jet f'producing means at the blade tips, a mixing tube having an air intake and a discharge end, conduit means connecting said air intake to a vpoint at the leading edge of the aircraft, conduit means Aconnectingthedischaige end of Said tube to the jet producing means, means for supplying and injecting high pressure and high temperature vaporized fuel to said tube thereby to entrain and aspirate air With the fuel to produce a combustible mixture, said last mentioned means including a fuel vaporizer, a conduit conducting the fuel through the vaporizer, a second mixing tube having an air intake and discharge end, means connecting the discharge end to said vaporizer, conduit means connecting the air intake of the last mentioned tube to first mentioned conduit means, and means including said fuel conducting conduit for supplying fuel and injecting the fuel into said last mentioned tube near said air intake to produce a combustible mixture for said vaporizer.

5. Jet propelled aircraft, including in combination, a propeller having blades and jet producing means at the blade tips, a mixing tube having an air intake and a discharge end, conduit means connecting said air intake to a point at the leading edge of the aircraft, conduit means connecting said discharge end of said tube to the jet producing means, means for supplying and injecting high pressure and high temperature vaporized fuel to said tube thereby to entrain and aspirate air with the fuel to produce a combustible mixture, said last mentioned means including a fuel vaporizer, means including a pump and conduit passing through the vaporizer for supplying said fuel, a second mixing tube having an air intake and discharge end, means connecting the discharge end connected to said vaporizer, conduit means connecting the air intake of the last mentioned tube to first mentioned conduit means, means including said fuel supplying conduit for supplying fuel and injecting the fuel into said last mentioned tube near said air intake to produce a combustible mixture for said vaporizer, and means for supplying fuel from another source and injecting it into said second mentioned tube.

6. Jet propelled aircraft, including in combination, a propeller rhaving blades and jet producing means at the blade tips, means including a pair of fuel vpumps for suppplying said jet producing means with a combustible mixture, propeller actuated means for driving one of said fuel pumps, and means including a selectively .operable motor for driving the other of said pumps.

7. Jet propelled aircraft, including in combination, a propeller having blades and jet producing means at the blade tips, means including a pair of fuel pumps and a pressure control valve connected to the discharge sides of both pumps for supplying said jet producing means with a combustible mixture, propeller actuated means forV driving one of said fuel pumps, and means including a selectively operable electric motor for driving the other pump, 8. An'aircraft power plant comprising in combination a rotatable propeller and jet producing means at the propeller tips, means connected to said jet producing means for supplying combustible mixture thereto including a mixing and velocity recovery tube having an air intake, injector nozzle means associated With saidA intake, a source of liquid fuel supply, pump means for raisingsaid fuel to a high pressure, a boiler connected to receive fuel from said pump means vand for converting said liquid fuel under high pressure to the vapor phase, and means for conducting said vaporized fuel at high pressure to said injector nozzle means so that vaporized fuel issuing at high velocity from said nozzle means will entrain air to form a combustible mixture stream in said mixing tube v.wherein the high velocity of said mixture stream Will be recovered as pressure so that mixture is supplied to said jet producing means in a compressed state.

K THELMA MCCOLLUM, Eecutria: of the Last Will and Testament of He'nTyIJ. De N. McCollum, Deceased.

REFERENCES CITED The following references are of record in the le of this patent:

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